[saturn@21004872 bin]$ ./ccache
ccache, a compiler cache. Version 2.4
Copyright Andrew Tridgell, 2002

Usage:
	ccache [options]
	ccache compiler [compile options]
	compiler [compile options]    (via symbolic link)

Options:
-s                      show statistics summary
-z                      zero statistics
-c                      run a cache cleanup
-C                      clear the cache completely
-F <maxfiles>           set maximum files in cache
-M <maxsize>            set maximum size of cache (use G, M or K)
-h                      this help page
-V                      print version number

[saturn@21004872 bin]$ ln -s ccache  mycc
[saturn@21004872 bin]$ ls -l ccache mycc
-rwxrwxrwx. 1 root root 31876  9月 13 22:31 ccache
lrwxrwxrwx. 1 root root    20  9月 15 18:20 mycc -> ccache

[saturn@21004872 bin]$ ./mycc
mycc: No such file or directory

:ls -l mycc
lrwxrwxrwx 1 j users 6 2010-09-14 22:33 mycc -> ccache

:./mycc
mycc: No such file or directory

:export CCACHE_CC=gcc

:./mycc
gcc: no input files

[saturn@21004872 bin]$ ls -l mycc
lrwxrwxrwx. 1 root root 20  9月 15 19:14 mycc -> ccache

[saturn@21004872 bin]$ export CCACHE_CC=gcc

[saturn@21004872 bin]$ ./mycc
gcc: No such file or directory

$ which busybox
/bin/busybox
$ busybox
BusyBox v1.17.1 (2010-08-17 09:57:50 CEST) multi-call binary.
Copyright (C) 1998-2009 Erik Andersen, Rob Landley, Denys Vlasenko
and others. Licensed under GPLv2.
See source distribution for full notice.

Usage: busybox [function] [arguments]...
   or: function [arguments]...

        BusyBox is a multi-call binary that combines many common Unix
        utilities into a single executable.  Most people will create a
        link to busybox for each function they wish to use and BusyBox
        will act like whatever it was invoked as.

Currently defined functions:
        [, [[, acpid, addgroup, adduser, adjtimex, ar, arp, arping, ash, awk, basename, bb, bbconfig, bbsh, beep, blkid, bootchartd, brctl, bunzip2, bzcat, bzip2, cal, cat, catv, chat, chattr, chgrp, chmod, chown,
        chpasswd, chpst, chroot, chrt, chvt, cksum, clear, cmp, comm, conspy, cp, cpio, crond, cryptpw, cttyhack, cut, date, dd, deallocvt, delgroup, deluser, depmod, devmem, df, dhcprelay, diff, dirname, dmesg,
        dnsdomainname, dos2unix, dpkg-deb, du, dumpkmap, dumpleases, echo, ed, egrep, eject, env, envdir, envuidgid, ether-wake, expand, expr, false, fbset, fdflush, fdformat, fdisk, fgconsole, fgrep, find, findfs,
        flash_eraseall, flash_lock, flash_unlock, flashcp, flock, free, freeramdisk, fsck, fsck.minix, fsync, ftpd, fuser, getopt, getty, grep, gunzip, gzip, halt, hd, hdparm, head, hexdump, hostname, httpd, hwclock, id,
        ifconfig, ifdown, ifenslave, ifplugd, ifup, init, insmod, install, ionice, ip, ipaddr, ipcrm, ipcs, iplink, iproute, iprule, iptunnel, kbd_mode, kill, killall, killall5, klogd, last, length, less, linux32,
        linux64, linuxrc, ln, loadfont, loadkmap, logger, login, logread, losetup, lpq, lpr, ls, lsattr, lsmod, lspci, lsusb, lzcat, lzma, lzop, lzopcat, makedevs, makemime, man, md5sum, mdev, mesg, microcom, mkdir,
        mkdosfs, mke2fs, mkfifo, mkfs.ext2, mkfs.minix, mkfs.reiser, mkfs.vfat, mknod, mkpasswd, mkswap, mktemp, modinfo, modprobe, more, mount, mountpoint, mt, mv, nameif, nc, netstat, nice, nmeter, nohup, nslookup,
        ntpd, openvt, passwd, patch, pgrep, pidof, ping, ping6, pipe_progress, pivot_root, pkill, popmaildir, poweroff, printenv, printf, ps, pscan, pwd, raidautorun, rdate, rdev, readahead, readlink, readprofile,
        realpath, reboot, reformime, renice, reset, resize, rev, rm, rmdir, rmmod, route, rtcwake, run-parts, runlevel, runsv, runsvdir, rx, script, scriptreplay, sed, sendmail, seq, setarch, setconsole, setfont,
        setkeycodes, setlogcons, setsid, setuidgid, sh, sha1sum, sha256sum, sha512sum, showkey, sleep, smemcap, softlimit, sort, split, start-stop-daemon, stat, strings, stty, su, sum, sv, svlogd, swapoff, swapon,
        switch_root, sync, sysctl, syslogd, tac, tail, tar, tee, telnet, telnetd, test, tftp, tftpd, time, timeout, top, touch, tr, traceroute, traceroute6, true, tty, ttysize, tunctl, tune2fs, ubiattach, ubidetach,
        udhcpc, udhcpd, umount, uname, uncompress, unexpand, uniq, unix2dos, unlzma, unlzop, unxz, unzip, uptime, usleep, vconfig, vi, vlock, volname, wall, watch, watchdog, wc, wget, which, who, whoami, xargs, xz,
        xzcat, yes, zcat, zcip

$ ln -s /bin/busybox ls
$ ls -l ls
lrwxrwxrwx 1 i92guboj i92guboj 12 sep 16 10:07 ls -> /bin/busybox
$ ./ls
COPYING       README        ccache.1      ccache.h      cleanup.c     configure     execute.c     install-sh    mdfour.c      packaging     stats.c       unify.c       web
Makefile.in   args.c        ccache.c      ccache.yo     config.h.in   configure.in  hash.c        ls            mdfour.h      snprintf.c    test.sh       util.c
$